RIYADH - A Saudi-led coalition declared an end Tuesday to four weeks of air strikes in Yemen, saying the threat of Iran-backed rebels there had been removed and that operations are entering a political phase.

However, it left open the option of resuming strikes if the movements of the Houthi rebels warrant it, while adding that a naval blockade on the strategic country at the tip of the Arabian Peninsula will continue.

The announcement came as a US aircraft carrier was headed to the Arabian Sea, with Washington saying it was monitoring Iranian vessels suspected of carrying weapons to the rebels in violation of a UN embargo.

The coalition has “ended Operation Decisive Storm based on a request by the Yemeni government and President Abedrabbo Mansour Hadi,” its spokesman, Brigadier General Ahmed al-Assiri, said in Riyadh.

The operation, which began March 26, will continue until midnight.

A coalition statement said the next step would aim to resume the political process in Yemen, delivering aid and “fighting terrorism” in the country, home to a deadly Al-Qaeda franchise.

The Saudi defence ministry said the air strikes had managed “to successfully remove threats to Saudi Arabia’s security and that of neighbouring countries”.

The UN health agency said more than 900 people have been killed since the strikes were launched against rebels clashing with pro-government forces.

And the International Organisation for Migration announced a suspension of its evacuation efforts due to insecurity.

Amid reports of a nine-ship Iranian convoy in the area, the US Navy said it was sending in the USS Theodore Roosevelt and guided-missile cruiser USS Normandy.

Pentagon spokesman Colonel Steven Warren said media reports suggesting the Americans were preparing to prevent the Iranian convoy from reaching Yemen if it was carrying arms were “a bit over-cranked”.

“We don’t know what the Iranian convoy of ships plans to do, but we are watching them,” Warren said. “By having American sea power in the region, we preserve our options.”

Overnight, they pressed the strikes against the rebels and their allies in the security forces, as the civilian death toll from a Monday raid on a missile depot in the capital rose to 38.

A further 532 people were wounded when the twin strikes sparked powerful explosions that flattened nearby houses, medics said.

International Medical Corps aid agency said six of its staffers were wounded, and a warehouse containing medicine and other supplies was damaged in Monday’s strikes. Rebel spokesman Mohammed Abdulsalam denounced the strikes on the base as a “barbaric crime,” insisting the “aggression will only unite the Yemeni people”.

The coalition says it has carried out more than 2,000 strikes, gained complete control of Yemeni airspace and knocked out rebel infrastructure.

Meanwhile, Iran welcomed the Saudi-led coalition’s announcement that it is ending a four-week air war in Yemen, saying it was a “step forward” to reaching a political settlement in the country.

“The establishment of a ceasefire and a stop to the killing of innocent and defenceless people is a step forward,” foreign ministry spokeswoman Marzieh Afkham said, quoted by the official IRNA news agency.

According to Reuters, senior Huthi leaders said political deal to end Yemen conflict has almost been reached.